Halliwill, JohnLarson, Emily2024-03-252024-03-25https://hdl.handle.net/1794/29301Much like exercise, heat stress is a profound thermoregulatory, cardiovascular, and autonomic stressor which may promote a distinct post-stress recovery period marked by altered cardiovascular support of blood pressure. For example, several studies have noted a sustained reduction in blood pressure following a single session of heat exposure or “post-heating hypotension,” which is comparable to the sustained hypotension which follows a single session of exercise. While post-heating hypotension, like post-exercise hypotension, may act as a valuable “window of opportunity” in promoting blood pressure management, very little is known about the mechanisms supporting blood pressure regulation during recovery from passive heat stress. Furthermore, as advancing age increases the prevalence of hypertension and alters the thermoregulatory and cardiovascular responses to acute heat stress, it is clinically and scientifically important that investigations into the post-heating recovery period are conducted in both young and older individuals. This dissertation aimed to characterize and compare the systemic cardiovascular and carotid baroreflex support of blood pressure during recovery from whole-body, passive heating in young and older individuals. Temperature, central, and peripheral hemodynamics were evaluated in sixteen young and nine older individuals at normothermic baseline and during 60 min of passive heating (water perfused suit) and 2 h of normothermic recovery. The neck pressure technique was additionally used to assess carotid baroreflex control of heart rate, the peripheral vasculature, and blood pressure across these time points. Contrary to our hypothesis, a single session of passive heat stress did not promote a sustained reduction in blood pressure in young or older individuals. Furthermore, the systemic cardiovascular and baroreflex responses which accompanied acute heat stress were transient and did not persist beyond 1 h of post-heating recovery in young or older individuals despite continued elevations in core temperature. While these findings do not support the notion that the post-heating recovery period promotes robust and sustained alterations in the cardiovascular support of blood pressure, our novel characterization of the time course of thermal, systemic cardiovascular, and neurovascular recovery from whole-body, passive heat stress in young and older individuals fills important gaps in knowledge as we begin to understand the post-heating recovery profile.en-USAll Rights Reserved.heat stressheat therapyolder adultspost-heatingrecoveryElectronic Thesis or Dissertation